> I am a teacher of a fourth year undergraduate course on language> processors which follows a classical structure (Aho et al.). This> year I was planning to give a short introduction to abstract machines> trying to present new (and famous) developments like the Java Virtual> Machine and Microsoft CLR in the context of older ones (like P-code,> etc.).

An interesting one is the pop11 (poplog) design. It's a fairly
classical VM but it was opened to the users. So anyone who wanted to
design a piece of syntax of their own, could define that syntax in
terms of the VM operations, that would then get compiled to native
code. This was used in the poplog system, that besides pop11 contained
prolog, ml and common lisp.